全文获取类型
收费全文 | 4385篇 |
免费 | 380篇 |
出版年
2022年 | 25篇 |
2021年 | 74篇 |
2020年 | 40篇 |
2019年 | 53篇 |
2018年 | 78篇 |
2017年 | 72篇 |
2016年 | 106篇 |
2015年 | 176篇 |
2014年 | 199篇 |
2013年 | 228篇 |
2012年 | 297篇 |
2011年 | 311篇 |
2010年 | 177篇 |
2009年 | 182篇 |
2008年 | 233篇 |
2007年 | 254篇 |
2006年 | 221篇 |
2005年 | 220篇 |
2004年 | 215篇 |
2003年 | 207篇 |
2002年 | 203篇 |
2001年 | 87篇 |
2000年 | 70篇 |
1999年 | 66篇 |
1998年 | 59篇 |
1997年 | 41篇 |
1996年 | 33篇 |
1995年 | 57篇 |
1994年 | 36篇 |
1993年 | 43篇 |
1992年 | 47篇 |
1991年 | 47篇 |
1990年 | 54篇 |
1989年 | 46篇 |
1988年 | 43篇 |
1987年 | 29篇 |
1986年 | 36篇 |
1985年 | 25篇 |
1984年 | 24篇 |
1983年 | 22篇 |
1982年 | 23篇 |
1981年 | 22篇 |
1979年 | 21篇 |
1978年 | 18篇 |
1976年 | 29篇 |
1975年 | 19篇 |
1974年 | 22篇 |
1973年 | 19篇 |
1971年 | 16篇 |
1970年 | 19篇 |
排序方式: 共有4765条查询结果,搜索用时 31 毫秒
71.
Paul Messner Max Wellan Wolfgang Kubelka Uwe B. Sleytr 《Applied microbiology and biotechnology》1993,40(1):7-11
After periodate oxidation and incubation with dithiodipropionic acid dihydrazide cross-linking of the crystalline surface layer (S-layer) glycoproteins of Clostridium thermohydrosulfuricum L111-69 and Bacillus alvei CCM 2051 was achieved specifically through the glycan chains. The cross-linked S-layers were used for the immobilization of chemically synthesized, spacer-linked, tumour-associated T-disaccharide [Gal(13)GalNAc]. Electron microscopical evaluation of the resulting conjugates showed densely packed, multilayered S-layer structures loaded with the immobilized ligand. After reductive cleavage of the disulphide bond of dithiodipropionic acid by dithiothreitol, monomeric haptenated S-layer conjugates could be obtained. Both the cross-linked and the monomeric type of conjugate might be useful for assessment of specific immune responses, which, in general, can be elicited by those artificial antigens.
Correspondence to: P. Messner 相似文献
72.
Wolfgang Kaul Uwe Rossow Carl-Christian Emeis 《Applied microbiology and biotechnology》1993,39(4-5):574-576
Several different bacteria and fungi capable of degrading yeast cell walls were isolated in the course of a screening programme. One Streptomyces and one Acremonium strain were found to degrade yeast cell walls extremely well. Both isolates produced enzymes in liquid culture that could be used for protoplasting of Sporobolomyces salmonicolor (DSM 70851) and Rhodotorula rubra (DSM 70403). This fact is quite remarkable as, so far, S. salmonicolor could not be protoplasted by commercially available enzymes.
Correspondence to: W. Kaul 相似文献
73.
The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers L11045 (human LMP7) and L11145 (mouse Lmp-7). 相似文献
74.
Mark H. Brand 《Plant Cell, Tissue and Organ Culture》1993,35(3):203-209
Shoot tip cultures of Amelanchier arborea Michx.f. were grown on Murashige & Skoog or Woody Plant (WP) medium containing 4.4 M benzyladenine and various concentrations of agar. Increases in agar concentration affected various culture growth variables, decreased culture hyperhydricity and increased tissue nitrate concentration. Additions of ammonium nitrate to cultures grown on WP medium containing 0.4% agar increased all growth variables measured except percent dry weight. Hyperhydricity and tissue nitrate concentration also increase in response to increasing ammonium nitrate in the medium. Since hyperhydricity was shown to be both positively and negatively correlated with increases in tissue nitrate content, it is unlikely that tissue nitrate level alone directly affects hyperhydricity.Abbreviations BA
benzyladenine
- MS
Murashige & Skoog
- WP
Woody Plant 相似文献
75.
76.
Summary For the first time for a Neotropical ant and for Myrmicinae, the searching behavior and specialized predation of spirobolid millipede eggs byStegomyrmex vizottoi Diniz will be described. The relationship between morphology and habits is studied, as are nest architecture and distribution of the ant population in the nest chambers. We also report on some observations of behavior in the field and laboratory.We dedicate this paper to William L. Brown Junior, on the occasion of his 70th birthday. 相似文献
77.
D Restrepo Y Okada J H Teeter L D Lowry B Cowart J G Brand 《Biophysical journal》1993,64(6):1961-1966
The sense of smell allows terrestrial animals to collect information about the chemical nature of their environment through the detection of airborne molecules. In humans smell is believed to play an important role in protecting the organism from environmental hazards such as fire, gas leaks and spoiled food, in determining the flavor of foods, and perhaps in infant-parent bonding. In addition, the study of human olfaction is relevant to a number of medical problems that result in olfactory dysfunction, which can affect nutritional state, and to the study of the etiology of neurodegenerative diseases which manifest themselves in the olfactory epithelium. Although much is known about behavioral aspects of human olfaction, little is understood about the underlying cellular mechanisms in humans. Here we report that viable human olfactory neurons (HON) can be isolated from olfactory tissue biopsies, and we find that HON respond to odorants with an increase in intracellular calcium concentration ([Cai]). 相似文献
78.
79.
Uwe Karsten Gisela Papsdorf Annedore Pauly Borivoj Vojtesek Roland Moll E. Birgitte Lane Henrik Clausen Peter Stosiek Michael Kasper 《Differentiation; research in biological diversity》1993,54(1):55-66
Abstract. Normal (non-transformed) human mammary epithelial cell lines derived from reduction mammoplasties were analyzed by immunocytochemistry with more than 80 monoclonal antibodies (mAbs) and other specific reagents to tissue-specific and developmentally regulated antigens at different passage levels. A subpopulation of poorly differentiated, proliferating epithelial cells, corresponding to the 'selected' cell type of late passages, is shown to be characterized by a new marker, the histo-blood group antigen H type 2, probably carried on a membrane-bound glycolipid. These cells also express a number of other onco-developmental carbohydrate antigens [Ley , Lex , sialosyl-Lea , precursor of Thomsen Friedenreich antigen (Tn ), but not Thomsen-Friedenreich antigen and sialosyl-Tn ]. Their cytokeratin (CK) phenotype, as assessed by reactivity with monospecific mAbs and two-dimensional gel electrophoresis, is CK 5, 6, 14 and 17, with CK 19 being consistently absent, and varying minor amounts of CK 7, 8 and 18, as well as 15 and 16. The reactivity of these cells with a panel of 11 mAbs specific for CK 18 varies considerably even after cloning, indicating heterogeneity of epitope expression or accessibility. Our data strongly suggest that the H type 2+ cells develop from the basal cell layer of the mammary gland. 相似文献
80.